Anti-microbial and oxidative co-polymer

ABSTRACT

A water-insoluble polymeric oxidizing medium is contemplated that has a plurality of polymerized N-pyridinium vinylbenzyl triiodide or tribromide moieties whose pyridinium rings bear two substituents, R 1  and R 2 , that are independently a hydrido or a C 1 -C 4  alkyl group, and correspond in structure to the formula  
                 
A process for preparing aseptic water and an apparatus useful for carrying out that process, both of which utilize a contemplated polymeric oxidizing medium are disclosed, as are processes for oxidizing trivalent arsenic or antimony to pentavalent arsenic or antimony and for removing arsenic from water. Alumina particles containing meta-periodate, iron or manganese are also disclosed that can be used to sorb pentavalent arsenic and antimony, as well as cobalt and mercury.

CROSS-REFERENCE TO RRELATED APPLICATION

This claims benefit of provisional application Ser. No. 60/260,131 filedJan. 5, 2001 and provisional application Ser. No. 60/256,297, filed Dec.18, 2000, whose disclosures are incorporated by reference.

TECHNICAL FIELD

The present invention relates to an anti-microbial and oxidativeco-polymer, and more particularly to an anti-microbial and oxidativeco-polymer medium that contains polymerized N-pyridinium vinylbenzyltriiodide that is substantially free of water-elutable iodine.

BACKGROUND ART

Lambert et al., U.S. Pat. No. 3,923,655, describe the desirability of aconvenient method of providing oxidation/disinfection on demand for usewith potable and recreational water. Those workers note that there arerelatively few ways to chemically treat water so that microorganisms aredestroyed without leaving behind residual bactericide. The most commonlyused treatment is that with chlorine. Other halogens such as bromine andiodine have been used much less frequently, and their usefulness haslargely been left to the treatment of swimming pools. Ozone is the onlyother substance used in large scale treatments.

The Lambert et al. patent teaches the use of strong base anion exchangepolymers containing a bactericidally effective amount of triiodide ions(I₃ ⁻)for killing bacteria, while being said to be essentially free ofwater-elutable oxidizing iodine. The preferred strong base anionexchange resin used is a quaternary ammonium resin that is first reactedwith an alkylating agent to eliminate residual tertiary amine groups.

The need for demand oxidizers/disinfectants; i.e., materials thatoxidize and/or disinfect when confronted with a need for such oxidationor disinfection as when contacted with a microbe, is as great now as itwas when the Lambert et al. patent was issued. Safe drinking water hasbecome more scarce with increasing population growth, especially inunderdeveloped countries where chlorination and other direct chemicaltreatment or boiling are not viable options. In addition, in moreaffluent countries, the need for microbial control water for swimmingpools, decorative fountains, private wells and ponds has increaseddramatically in the years since the issuance of U.S. Pat. No. 3,923,665.

The preferred resin used in the Lambert et al. disclosure is understoodto be a co-polymer containing styrene and chloromethylstyrene groupsthat is cross-linked by divinylbenzene. Those polymerizedchloromethylstyrene (vinylbenzyl chloride) groups can be reacted withtrimethyl amine to form the quaternary ammonium groups of the strongbase anion exchanger. Alternatively, dimethylamine can be reacted withthe chloromethyl groups and the tertiary amines so formed can bequaternerized by reaction with an alkylating agent such as methyl iodideor dimethyl sulfate.

The co-polymer strong base anion exchange compositions described in theLambert et al, patent are not widely used in the aforementionedapplications because, in practice, they are found to be unstable andbleed objectionable and irritating levels of iodine into the water beingtreated. This finding is contrary to the express teachings of thepatent.

Another problem with the alkylated strong base anion exchange materialsdescribed by Lambert et al., and particularly the alkylated quaternaryammonium materials, is that they are themselves not stable, but candecompose to form tertiary amine-containing materials, iodine and methyliodide. Tertiary amines are poor ligands for triiodide ion and permitthat ion to be easily removed. In addition, methyl iodide is listed asbeing a highly toxic cancer suspect agent in R. J. Lewis, Sax'sDangerous Properties of Industrial Materials, 9th ed., Van NostrandReinhold, New York, (1996) page 2262. Lambert et al. teach that oneshould realkylate a resin prior to forming the triiodide form so thatany tertiary amine present would be removed.

Lambert et al. teach that one of the possibly useful resins is anN-alkylated poly(vinylpyridine) as discussed in U.S. Pat. No. 2,739,948.The preparation and use of a similar material is taught in U.S. Pat. No.5,908,557 for the removal of arsenic anions from aqueous solutions.Those latter co-polymers are known to be incompletely quaternized and totherefore contain some unalkylated, tertiary amine. It is believed thatthe materials of U.S. Pat. No. 2,739,948 also contained some tertiaryamine.

Arsenic poisoning of drinking water has reached catastrophic proportionsin some parts of the world. In West Bengal, India, for example, anestimated 200,000 people currently suffer from arsenic-induced skinlesions, some of which have advanced to pre-cancerous hyperkeratoses. InBangladesh, it is estimated that more than 3 million of theapproximately 5 million existing wells are arsenic-contaminated,affecting up to 70 million people--tens of thousands exhibiting symptomsof arsenicosis. The international health community has suggested atarget arsenic concentration of no more than 10 parts per billion (ppb)arsenic in drinking water, as compared to the present 50 ppb standard.

In the United States, arsenic in drinking water is designated as apriority contaminant under the 1986 Safe Drinking Water Act andamendments thereto. Since 1974, an arsenic Maximum Contaminant Level(MCL) of 50 ppb has been in effect in the United States. As a result ofmore recent findings pertaining to health risks associated withpopulations exposed to high concentrations of arsenic in drinking water,the United States Environmental Protection Agency (EPA) recommends thelowering of the MCL for arsenic from 50 ppb to 2 ppb.

In the United States alone, more than 12,000 public water utilitieswould fail to meet the more stringent proposed arsenic standard. Oneestimate places the cost of compliance for the 2 ppb MCL proposal inexcess of $5 billion/year. The number of private wells in the UnitedStates that fail to meet the existing 50 ppb or proposed 2 ppb MCL forarsenic is unknown. It is believed that in many areas in the USA, manythousands of private wells produce drinking water with potential,serious health risks for the households depending on self-produced waterbecause of arsenic contamination.

Arsenic is found in several oxidation states. Typically, arsenic ispresent in aqueous solutions in the oxidation state of plus five (As⁺⁵,pentavalent) and to a lesser extent the oxidation state of plus three(As⁺³, trivalent). There is no significant reported cation chemistry forarsenic, but organic arsenic salts are known for both oxidation states(e.g. K[As(C₆H₄O₂)₂]).

Examples of trivalent arsenic compounds are the halides (AsCl₃, AsCl₂ ⁺,and AsF₃). The halides are readily hydrolyzed to arsenious acid (H₃AsO₃)or it acid-dissociated forms (HAsO₃ ²⁻). The oxide form is As₂O₃. Thetrivalent arsenic compounds to be separated from aqueous solutions, mostlikely in an ionized form of H₃AsO₃, in a process of the invention arecollectively referred to herein as “trivalent arsenic”.

As⁰ can be oxidized by concentrated nitric acid to pentavalent arsenicas arsenic acid (isolable as H₃AsO₄.

H₂O), which is a moderately strong oxidizing agent in solution. Thecorresponding halides are also known (e.g. AsCl₅, AsCl₄ ⁺). Thepentavalent arsenic compounds to be separated from aqueous solutions aremost likely an ionized form of H₃AsO₄. In a process of the invention,such pentavalent arsenic compounds are collectively referred to hereinas “pentavalent arsenic”.

Analytical surveys taken of drinking water around the world usually givea total arsenic level and fail to distinguish contributions frompentavalent arsenic or trivalent arsenic, even though trivalent arsenicis considerably more toxic than pentavalent arsenic. The failure todistinguish the valence of arsenic present in drinking water furtherconfuses the logical assignment of MCL values because although a levelof 2 ppb of pentavalent arsenic may cause no deleterious health effects,an equivalent level of trivalent arsenic can have negative healthconsequences.

There is an urgent need for a technology that will remove arsenic fromdrinking water to provide safe levels of arsenic regardless of theoxidation state of the arsenic in an efficient, economical andenvironmentally sound manner. It is desirable that such technology beflexible and sufficiently robust in order to address the requirements oflarge municipal water utilities, private wells in developed countriesand contaminated water sources in undeveloped countries. It is alsodesirable that an arsenic removal method is able to remove arsenic fromwater without removing all of the trace minerals that contribute to itsflavor.

A number of technologies have been described in the art to removearsenic from drinking water, also known as “arsenic remediation”. Thesetechnologies of the art include iron co-precipitation, reverse osmosis,alumina adsorption and classical ion-exchange with anion exchangeresins. These methods can be effective at removing pentavalent arsenic,but trivalent arsenic defies efficient removal. In a report entitled“National Compliance Assessment and Costs for the Regulation of Arsenicin Drinking Water” (January, 1997) prepared by the University ofColorado at Boulder, more than a dozen putative methods are evaluatedfor arsenic removal efficiency and cost. None of the evaluated methodsdescribed exhibited arsenic removal efficiencies greater than 95percent. In addition, the prior art methods do not offer the simplicityof use required for private well treatment or for less developed areasof the world where reliable electrical power is unavailable. In thesesituations, a “point of use” treatment is necessary or water must betransported in for use.

U.S. Pat. No. 5,908,557 describes an oxidizing and separation medium forconverting trivalent arsenic into pentavalent arsenic, and removing thepentavalent form. That patent relies on the use of polymerized N-alkylpyridinium triiodide adsorption medium to oxidize and remove thearsenic. Those polymerized N-alkyl pyridinium triiodide moieties can bedepicted as shown below, wherein the parentheses are used to show thatthe polymerized N-alkyl pyridinium triiodide moieties are distributedrepeatedly through out the co-polymer thereby forming a plurality ofN-alkyl pyridinium triiodide moieties. As is noted at column 5, lines28-31 of that patent,

not all of the of the pyridine nitrogen atoms are alkylated, therebyleaving some tertiary pyridine nitrogens. More importantly, the presenceof N-alkyl groups permits dealkylation of the polymer to occur over timeleading to an increased amount of tertiary amine and a methyl halidethat can be carcinogenic.

Several other common water contaminants, such as iron(II), antimony,sulfate, nitrate and color-causing contaminants can negatively influencearsenic remediation by the known methods. Classical ion-exchange withanionic resins of the art suffer from poor efficiency (90 percent), lowcapacity (1500 bed volumes) and severe reduction in capacity and bindingefficiency when competing ions such as sulfate are present in amounts of50 ppm or more. Classical ion-exchange media suffer from poor longevitywhen challenged with a matrix of hard well water. It is estimated by theaforementioned University of Colorado report that 25 percent of suchclassical resins would have to be replaced on an annual basis.

The currently-favored plan for removing arsenic from drinking water inBangladesh is to permit the water to sit for several hours exposed toair, allowing the iron in the water to oxidize, which should causearsenic to precipitate out and settle.

There remains, therefore, a need for a simple-to-use adsorbent forremoving dissolved arsenic from water that is stable and that exhibitsan arsenic removal efficiency greater than 95 percent. Another importantconsideration in water remediation is consumer acceptance. The safety,flavor and cost of the water are all important factors in the provisionof drinking water.

It is thus seen that an improved co-polymer triiodide resin is needed toprovide demand oxidation/disinfection. Such a material should be stableto decomposition, contain only quaternary ammonium groups while beingfree of tertiary amine groups, and should neither bleed iodine intosurrounding water, nor decompose to form an alkyl halide. The disclosurethat follows describes one such co-polymer and several of its uses.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention contemplates a water-insolublepolymeric medium having a plurality of polymerized N-pyridiniumvinylbenzyl triiodide or tribromide moieties whose pyridinium rings beartwo substituents, R¹ and R², that are independently a hydrido or a C₁-C₄alkyl group. An exemplary water-insoluble polymeric medium triiodide ortribromide can be illustrated by the structural formula

wherein the parentheses are used to show that the polymerizedN-pyridinium vinylbenzyl group is distributed repeatedly through out theco-polymer thereby forming a plurality of N-pyridinium vinylbenzyltriiodide or tribromide groups. In preferred embodiments, one of the R¹and R² substituents is C₁ alkyl group. More preferably, R1 and R²substituents are both hydrido groups. Preferably, the polymeric mediumhas a triiodide ion content of about 0.1 to about 1.0 moles per liter,that is more preferably about 0.2 to about 0.5 moles per liter ofco-polymer. The polymeric medium is preferably a solid, macroreticularchloromethylated styrene-divinylbenzene co-polymer that is reacted withpyridine or a mono- or disubstituted pyridine to form the correspondingpyridinium chloride that is further exchanged with triiodide ortribromide ions. A preferred, contemplated polymeric medium is free ofwater-elutable iodine or bromine, and is present as free-flowingparticles.

Another embodiment contemplates a process for forming an aseptic fluidsuch as water or air from a fluid that contains microbial contamination.A contemplated process comprises the steps of providing a vesselcontaining a water-insoluble polymeric medium having a plurality ofpolymerized N-pyridinium vinylbenzyl triiodide or tribromide moieties(groups) of the structure

wherein R¹ and R² are independently a hydrido or a C₁-C₄ alkyl group. Aninfluent of microbially contaminated fluid such as water that is clearand free from visible precipitate is introduced to the vessel to contactthe insoluble medium. The fluid is maintained in contact with theinsoluble medium for a time period sufficient for microbes present inthe influent to be killed by the triiodide ions and form aseptic fluid.The aseptic fluid is discharged from the vessel as an effluent.

The before-noted preferences for the polymeric medium are maintainedwhen that medium is used in a contemplated process. Pseudomonasaeruginosa and coliforms are particular microbes against which acontemplated polymeric medium is useful.

A process for oxidizing trivalent arsenic or antimony to pentavalentarsenic or antimony is contemplated. This process comprises thefollowing steps.

(a) A vessel is provided that contains a water-insoluble polymericoxidation medium comprising an oxidation medium having a plurality ofoxidizing sites that are polymerized N-pyridinium vinylbenzyl triiodideor tribromide moieties (groups) of the structure

wherein R¹ and R² are independently a hydrido or a C₁-C₄ alkyl group.

(b) An influent aqueous solution having trivalent arsenic or antimony isintroduced into the vessel to contact the insoluble oxidizing medium.

(c) The aqueous solution is maintained in contact with the insolubleoxidizing medium for a time period sufficient for the trivalent arsenicor antimony in the influent to react with the oxidizing sites to formpentavalent arsenic or antimony in the solution and reduced medium.

(d) The pentavalent arsenic-containing or antimony-containing solutionis separated from the reduced medium, typically as an effluent.

A process for removing arsenic from an aqueous solution is alsocontemplated and comprises the following steps.

a) A vessel is provided that contains a water-insoluble polymericoxidizing medium having a plurality of oxidizing sites that arepolymerized N-pyridinium vinylbenzyl triiodide or tribromide moieties asdescribed above.

b) A volume of an influent aqueous pre-sample solution that may containarsenic as water-soluble ions in the trivalent or pentavalent form at aconcentration greater than about 2 parts per billion is introduced intothe vessel to contact the insoluble oxidizing adsorption medium.

c) The pre-sample solution is maintained in contact with the insolubleoxidizing medium for a time period sufficient for trivalent arsenicpresent in the influent to react with the oxidizing sites to oxidize topentavalent arsenic and form a sample solution and reduced medium.

d) The pentavalent arsenic-containing sample solution is contacted witha pentavalent arsenic binding medium to form medium-bound arsenic and anaqueous composition.

e) The aqueous composition is discharged from the vessel as an effluenthaving final arsenic concentration that is significantly less, at leastabout 95 percent less, than the initial concentration, and typicallyabout zero to about 2 parts per billion arsenic. A similar process canbe used to remove trivalent and pentavalent antimony.

A more general process for oxidizing a water-soluble metal ion from afirst oxidation state to a second, higher oxidation state is alsocontemplated. This process comprises the following steps.

a) A vessel is provided that contains a water-insoluble polymericoxidizing medium having a plurality of oxidizing sites that arepolymerized N-pyridinium vinylbenzyl triiodide or tribromide moieties asdescribed above.

b) A volume of an influent aqueous solution that containing metal ionsof a first oxidation state as water-soluble ions is introduced into thevessel to contact the insoluble oxidizing medium to form a solid/liquidadmixture.

c) The solid/liquid admixture is maintained for a time period sufficientfor the metal ions present in the influent to react with the oxidizingsites to oxidize to a second, higher oxidation state to form a samplesolution and a reduced medium.

d) The sample solution is then separated from the reduced medium.

Another aspect of the invention contemplates modified particulatealumina containing meta-periodate ions substantially homogeneouslysorbed throughout the particles. The meta-periodate ions are present inan amount of about 0.1 to about 0.15 molar in a gravity-settled volumeof particles in deionized water.

A further aspect of the invention contemplates modified aluminaparticles containing iron or manganese or both substantiallyhomogeneously sorbed throughout the particles. The iron or manganese ispresent in an amount of about 0.05 to about 0.15 molar in agravity-settled volume of particles in deionized water. The particlescontain an oxidized iodine species and are substantially free ofmolecular iodine.

A process for removing arsenic or antimony +3 or +5 ions from a watersupply is also contemplated. That process comprises the following steps.

a) An aqueous solution that contains arsenic or antimony +3 or +5 ionsin a concentration greater than about 2 parts per billion is contactedwith modified alumina particles. Those modified alumina particlescontain iron or manganese or both sorbed substantially homogeneouslydistributed throughout in an amount of about 0.05 to about 0.15 molar asmeasured in a gravity-settled volume of particles in deionized water.The particles also contain an oxidized iodine species and aresubstantially free of molecular iodine.

b) That contact is maintained for a time period sufficient for arsenicor antimony +3 or +5 ions present to be sorbed by the particles to formarsenic- or antimony-containing particles and an aqueous solution havinga lessened amount of arsenic or antimony.

c) The arsenic- or antimony-containing particles are separated from theaqueous solution having a lessened amount of arsenic or antimony.

A still further contemplated aspect of this invention is an apparatusfor preparing an aseptic fluid such as water. That apparatus comprises avessel having an inlet, an outlet and a water-insoluble polymeric mediumin a polymeric medium-containing region. The water-insoluble polymericmedium is as discussed before and is supported and contained within themedium-containing region. In one preferred embodiment, the vesselincludes a first flow-permitting support positioned between the outletand the medium-containing region. Preferably also, the vessel includes asecond flow-permitting support positioned between the inlet and themedium-containing region. The inlet and outlet are preferably separatedfrom each other, and are more preferably are at opposite ends of theapparatus.

The present invention has several benefits and advantages.

One benefit is that it provides an inexpensive oxidizing solid phasemedium that can oxidize arsenic +3 and antimony +3 ions to thecorresponding +5 ions, and also kill bacteria.

An advantage of the invention is that a contemplated solid phaseoxidizing medium changes color as the oxidant is utilized and therebyindicates its own degree of use.

Another benefit of the invention is that the oxidant of a contemplatedsolid phase oxidizing medium does not bleed from the medium, whichbleeding can cause off-odors to the surrounding environment.

Another advantage of the invention is that it provides a solid phasealumina-based medium that can sorb (absorb or adsorb) arsenic +5 andantimony +5 ions from aqueous media.

A further benefit of the invention is that a contemplated solid phasealumina-based medium containing sorbed arsenic +5 or antimony +5 bindsthose ions tightly, thereby permitting disposal of spent medium in aland fill without worry of leaching of the bound ions to theenvironment.

A further advantage of the invention is that a contemplated solid phasealumina-based medium containing sorbed mercury can be heated in a retortto release the mercury for collection and permit reuse of the medium.

Still further benefits and advantages of the invention will be apparentto the worker of ordinary skill from the disclosure that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic representation of a separation vessel useful inan embodiment of the invention.

FIG. 2 shows a schematic representation of another separation vesseluseful in an embodiment of the invention.

FIG. 3 shows a schematic representation of yet another separation vesseluseful in an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an anti-microbial and oxidativewater-insoluble polymeric medium (often merely referred to as apolymeric medium) and its use in the preparation of aseptic water andfor converting trivalent arsenic to pentavalent arsenic (As⁺³ As⁺⁵) insuch water.

Thus, one aspect of the present invention contemplates a water-insolublepolymeric oxidizing medium. A contemplated polymeric oxidizing medium isa co-polymer that has a plurality of polymerized N-pyridiniumvinylbenzyl triiodide or tribromide moieties whose pyridinium rings beartwo substituents, R¹ and R², that are independently a hydrido or a C₁-C₄alkyl group. The polymerized N-pyridinium vinylbenzyl triiodide ortribromide moieties comprise oxidizing sites in the co-polymer medium.An exemplary water-insoluble polymeric medium is preferably a solid atambient temperatures and can be illustrated by the structural formula

wherein the parentheses are used to show that the polymerizedN-pyridinium vinylbenzyl group is distributed repeatedly through out theco-polymer thereby forming a plurality of N-pyridinium vinylbenzyltriiodide or tribromide groups. In preferred embodiments, one of the R¹and R² substituents is C₁ alkyl group. More preferably, R¹ and R²substituents are both hydrido groups so that the N-pyridiniumvinylbenzyl triiodide or tribromide groups of the polymeric mediumcorresponds in structure to the formula

Preferably, the polymeric medium has a triiodide or tribromide ioncontent of about 0.1 to about 1.0 moles per liter, that is morepreferably about 0.2 to about 0.5 moles per liter of co-polymer. Thetriiodide or tribromide content is preferably about one-third thecontent of pyridinium groups so that all of the iodide or bromide ionthat is released upon reductive decomposition of triiodide or tribromidecan be taken up by the polymeric medium. Triiodide is more preferred ascompared to tribromide.

The polymeric medium is preferably a macroreticular chloromethylatedstyrene-divinylbenzene co-polymer that is reacted with pyridine or anappropriate mono- or disubstituted pyridine to form the correspondingpyridinium chloride, whose chloride ion is further exchanged withtriiodide or tribromide ions. A preferred, contemplated polymeric mediumis free of water-elutable iodine or bromine, and is present asfree-flowing particles, although a contemplated polymeric medium can bepresent as a film.

In preferred practice, the R¹ group is hydrido and R² group is at the4-position, and is preferably a H (hydrido) group. More preferably, bothR¹ and R² are hydrido groups so pyridine itself is used. When either R¹or R² is other than hydrido, that R group is preferably a methyl (C₁)group. Exemplary mono- and di-substituted pyridines where thesubstituent R¹ or R² group is a methyl (C₁) group include α-, β-, andγ-picolines, and the 3,4-, 3,5-, 2,3-, 2,4-, 2,5- and 2,6-lutidines.

A preferred process for preparing a contemplated ion exchange resinusing pyridine itself or a mono- or di-C₁-C₄ alkyl pyridine [R¹=H orC₁-C₄ alkyl and R²=H or C₁-C₄ alkyl] is illustrated generally inSynthesis Scheme 1 shown below.

As is seen, a preferred reaction sequence begins with the preparation ofchloromethylated cross-linked polystyrene such as the beads whosesynthesis is well-known from the preparation of commercially availablequaternary ammonium ion-containing ion exchange resins. Generallyspherical beads are a preferred form of a contemplated resin and suchbeads are utilized illustratively herein.

In one procedure, cross-linked polystyrenes beads are first preparedthat are subsequently chloromethylated by reaction with chloromethylmethyl ether in the presence of aluminum chloride or similarFriedel-Crafts catalyst. The resulting chloromethylated beads arethereafter reacted with pyridine or a substituted pyridine.

Another process co-polymerizes vinyl benzyl chloride (chloromethylstyrene) and a cross-linker in a manner similar to that used to preparepoly(styrene-co-chloromethylstyrene) resin beads containing 2 percentDVB cross-linker that are described by Tomoi et al. J. Am. Chem. Soc.103:3821 (1981).

Exemplary cross-linked chloromethylated polystyrenes can be obtainedfrom Sigma Chemical Co. of St. Louis, Mo. under the designationMerrifield's Peptide Resin. These beads are of 200-400 mesh size and areavailable at 0.9-1.5 milliequivalents (meq) of chloride per gram,0.4-0.9 meq/g, both at 1% cross-link, and about 1 meq/g at 2%cross-link. Similar 200-400 mesh materials are also available from AcrosOrganics, Fisher Scientific, Pittsburgh, Pa. that are said to contain2-2.5 meq/g chlorine at both 1% and 2% cross-link.

It should be apparent to those skilled in the art of water purificationthat a water-insoluble polymeric adsorption or oxidizing medium can besolid or liquid. It should also be understood that the N-pyridiniumvinylbenzyl-containing moieties need not themselves form part of apolymer backbone, but can also be grafted onto a previously made polymerusing usual grafting techniques for vinylbenzyl chloride, followed byreaction with a pyridine and triiodide or tribromide exchange to form anadsorption medium having N-pyridinium triiodide or tribromide moietyoxidation/adsorption sites.

Suitable cross-linking materials for use in the present inventioninclude divinylbenzene (DVB), trimethylolpropane triacrylate,trimethylolpropane trimethacrylate, 1,6-hexanediol dimethacrylate,1,10-decanediol dimethacrylate and the like as are well known in theart. Divinylbenzene is a particularly preferred cross-linking agent, andfrequently contains ethyl styrene as an impurity. A person of ordinaryskill in the art will appreciate that one can use other cross-linkingmaterials without extending beyond the scope of the present invention.

Contemplated polymeric media in particulate form can be sized from about400 mesh to about 10 mesh, as may be desired depending upon the flowrate of water through a column as is usually used in the preparation ofaseptic water. Preferably, the particles are of about 20 to about 35mesh (about 850 μm to about 500 μm), and more preferably about 25 toabout 30 mesh, or about 710 to about 600 μm. The particle sizedistribution of an exemplary batch of polymeric medium is shown inExample 1, hereinafter.

Additionally, a contemplated polymeric medium in triiodide form is darkbrown to brown-purple in color, whereas the tribromide form is ared-orange color. A co-polymer free of triiodide or tribromide ions suchas a precursor or spent medium is tan so that one can tell by a colorchange when the polymeric medium is spent and should be replaced.

A contemplated adsorption medium is seemingly similar to the strong basetrialkyl ammonium media described in the Lambert et al. U.S. Pat. No.3,923,655, and also seemingly similar to the N-alkyl pyridiniumgroup-containing media of the Smith et al. U.S. Pat. No. 5,908,557.However, in each instance, the medium contemplated here is not onlydifferent in structure from each of those other media, but alsodifferent in its binding characteristics for various ions.

Thus, as already noted, the media of both the Lambert et al. and Smithet al. patents contain N-alkyl quaternary ammonium moieties. Thosegroups can decompose to form halomethanes, which are believed to becarcinogenic. A medium contemplated here, with its pendent benzylpyridinium group, cannot decompose similarly. Additionally, as shown inthe Examples hereinafter, a medium as taught in Lambert et al. in thetriiodide form loses iodine to its surroundings, whereas a contemplatedmedium does not. Furthermore, a contemplated medium and that disclosedin the Smith et al. patent, when both are in their chloride forms, binddichromate ion at very different rates, even though the availablebinding sites were in great excess over the amount of dichromatepresent.

Another embodiment of the invention contemplates a process for formingan aseptic fluid such as water or air from a fluid containing microbialcontamination. A contemplated process can be used with air as well asfresh or salt water in that elution of a previously discussed polymericmedium with 2 molar sodium chloride did not remove a noticeable amountof iodine.

One contemplated process comprises the steps of providing a vesselcontaining a water-insoluble polymeric oxidizing medium having aplurality of polymerized N-pyridinium vinylbenzyl triiodide ortribromide moieties (groups) of the structure

wherein R¹ and R² are independently a hydrido or a C₁-C₄ alkyl group.

An influent of microbially contaminated fluid such as water that isclear and free from visible precipitate is introduced to the vessel tocontact the insoluble medium. Thus, for example, the water contemplatedfor use in this process has some microbial load, but is not a highlycontaminated slime as might be found in a sewage treatment plant.Rather, water from a lake or river, ornamental pond or pond for thedisplay of aquatic fish and crustaceans is contemplated for use in aprocess. The water can be slightly turbid and can be filtered prior touse in a process to remove the turbidity.

The fluid such as water is maintained in contact with the insolublemedium for a time period sufficient for microbes present in the influentto be killed by the triiodide or tribromide ions and form an asepticfluid such as water. The aseptic fluid is discharged from the vessel asan effluent.

Exemplary microbes against which a contemplated process is usefulinclude Pseudomonas aeruginosa, coliform such as Klebsiella terrigenaand E. coli, Cryptosporidium, Giardia muris and Giardia lamblia,Legionella and the like. Pseudomonas aeruginosa and coliforms such as E.coli are particular microbes against which a contemplated polymericmedium is useful.

The before-noted preferences for the polymeric medium are maintainedwhen that medium is used in a contemplated process.

An apparatus for preparing an aseptic fluid comprising the abovepolymeric medium in a support vessel is also contemplated. Acontemplated support vessel is typically glass or plastic such aspolyethylene or polypropylene and is typically a chromatographic columnor cartridge. A contemplated vessel can include one or more inlets,outlets, valves such as stopcocks and similar appendages.

One contemplated support vessel is cylindrical and has an inlet forreceiving a fluid such as an aqueous solution prior to contact of thesolution with the contained polymeric medium and an outlet for theegress of water after contact with the medium. When the support vesselis a glass or plastic chromatographic column or cartridge, the vesselcan contain appropriate valves such as stopcocks for controlling aqueousflow, as are well-known, as well as connection joints such as Luerfittings. The inlet for receiving an aqueous liquid solution and outletfor liquid egress can be the same structure as where a beaker, flask orother vessel is used for a contemplated process, but the inlet andoutlet are typically different and are separated from each other when afluid such as air is utilized. Usually, the inlet and outlet are atopposite ends of the apparatus.

FIG. 1 provides a schematic drawing of one preferred apparatus forpreparing aseptic water. Here, the apparatus 10 is shown to include asupport vessel as a column 12 having an inlet 26 and an outlet 28 forwater. The outlet has an integral seal and is separable from the seal ata frangible connection 32. The apparatus 10 contains one or moreflow-permitting support elements. In one embodiment, a frit 22 supportspolymeric medium 16, and an upper frit 18 helps to keep the medium inplace during the introduction of an influent of aqueous solution.Contemplated frits can be made of glass or plastic such as high densitypolyethylene (HDPE). A HDPE frit of 35-45 μm average pore size ispreferred. A contemplated apparatus can also include a stopcock or otherflow-regulating device (not shown) at, near or in conjunction with theoutlet 28 to assist in regulating flow through the apparatus.

An above-described chromatographic column is typically offered for salewith a cap (not shown) placed into inlet 26 and snap-off (frangible)tube end 30. The polymeric medium in such a column is typically wet andequilibrated with aseptic water and can be used as part of abackpacker's kit for a hike or camping trip or the like for a personaway from aseptic water. It is preferred that the average diameter ofpolymeric medium particles be about 600 to about 750 μm when achromatographic column apparatus is prepared and used.

FIG. 2 provides a second schematic drawing of another preferredapparatus. Here, the apparatus 110 is shown to include a support vesselas a cartridge 112 having an inlet 126 and an outlet 128 for water. Acap 124 is preferably integrally molded with the inlet 126. The outlet128 is preferably integrally molded with the cartridge 112. Theapparatus 110 contains a porous support such as a frit 122 that supportspolymeric medium 116. An upper porous support such as a frit 118 helpsto keep the medium in place during the introduction of an influentaqueous sample or eluting solution. A contemplated apparatus can alsoinclude a stopcock or other flow-regulating device (not shown) at, nearor in conjunction with the outlet 128 to assist in regulating flowthrough the apparatus.

A contemplated cartridge such as a vessel of FIG. 2 is typicallyprovided with the polymeric oxidizing medium in a dry state, or wet withaseptic water. In addition, inlet 126 and outlet,128 are preferablystandard fittings such as Luer fittings that are adapted for easyconnection to other standard gas and/or liquid connections. Thisembodiment is particularly adapted for use in a person's sink as a finalfilter prior to use of the water, as where potable water is deliveredfrom a well. This embodiment containing dry polymeric medium is alsoparticularly adapted for use with air as the fluid. It is also preferredthat the average diameter of particles be about 600 to about 750 μm whena cartridge apparatus is prepared and used.

FIG. 3 illustrates a schematic diagram of yet another apparatus 210 forcarrying out the present invention. The apparatus 210 includes a supportvessel 212 having an inlet port 226 and an outlet port 228. The inletand outlet ports 226, 228 are positioned on a common end of the vessel212. This arrangement can be used where, for example, access to theentire vessel 212 is limited and attachment of connecting tubing (notshown) is facilitated by locating the ports 226, 228 near or adjacentone another.

The vessel 212 supports the polymeric oxidizing medium 216 therein to apredetermined height (corresponding to a volume) within the vessel 212.A dip pipe 230 is located within the vessel 212 in flow communicationwith the outlet port 228. The dip pipe 230 provides a path fordischarging treated (e.g., aseptic) water from the vessel 212.

Slits 232 or other openings are formed in the dip pipe 230 to provide aflow path from the vessel 212 to the interior of the pipe 230 and thusthe vessel outlet 228. The slits 232 or openings are sized accordinglyto prevent the loss of media 216 from the vessel 212. As with thepreviously described embodiments, a support, such as frit (not shown)can be placed over the polymeric media 216 to maintain the media 216 inplace in the vessel 212.

As will be readily understood from a study of FIG. 3, water is suppliedto the vessel 212 through the inlet port 226. The water “fills” thevessel 212 to an operational level. Treated water is drawn from theoutlet 228 through the dip pipe 230. The water flow through the dip pipe230 can only enter the pipe by flowing through the media 216. Thus, acompact, readily connected apparatus 210 by which to treat water isprovided.

One contemplated apparatus such as that of FIG. 1 can be readilyprepared by slurrying the polymeric medium in aseptic water. The slurryis added onto a flow-permitting support element such as a frit in avertically oriented support vessel such as a column. The medium ispermitted to settle under the force of gravity and can be packed moredensely using vibration, tapping or the like. Once a desired height ofmedium is achieved, any excess liquid is removed as by vacuum, a secondflow-permitting element such as another frit is inserted into the columnabove the medium and the cap is added.

To prepare another chromatographic column that can be used for acontemplated process, a portion of polymeric medium prepared asdiscussed above is slurried in aseptic water and aliquots of that slurryare transferred under nitrogen pressure to a 10 cm long glass Bio-Rad®column (1.4 mm inside diameter) equipped with polypropylene fittingsmanufactured under the trademark “Cheminert” by Chromatronix, Inc.,Berkeley, Calif. When the desired bed height is reached (correspondingto a bed volume of about 0.6 cm³), the medium is resettled byback-washing. The polymeric oxidizing medium is then rinsed with severalbed volumes of aseptic.

An apparatus shown in FIG. 2 can be prepared by adding a predeterminedweight of dry polymeric medium to the cartridge 112 containing moldedoutlet 128 and support frit 122. The thus filled cartridge is vibratedin a vertical orientation to achieve a constant height for the mediumbed, the upper porous support 118 is inserted, and the cap 124containing molded fluid inlet 126 is placed onto the device.

The present invention is also directed to a process for oxidizingtrivalent arsenic to pentavalent arsenic and removing objectionablelevels of arsenic from an aqueous solution also containing other ions.Typically, in order to reduce the arsenic concentration of drinkingwater to acceptable levels, the arsenic MCL should be at or below 50parts per billion (ppb), preferably at or below 10 ppb, and mostpreferably at or below 2 ppb.

A process for oxidizing trivalent arsenic ions in solution topentavalent arsenic ions is thus contemplated. In accordance with such aprocess, a vessel, also referred to as a flow-permissive container suchas a before described chromatographic column or mesh pouch is providedthat contains a water-insoluble polymeric oxidation medium having aplurality of oxidation sites that are polymerized N-pyridiniumvinylbenzyl triiodide or tribromide moieties (groups) of the structure

wherein R¹ and R² are independently a hydrido or a C₁-C₄ alkyl group.

A volume of an influent aqueous pre-sample solution that can containarsenic as water-soluble ions in the trivalent form at a concentrationgreater than about 2 parts per billion is introduced as an influent intothe vessel to contact the insoluble oxidizing medium. This solution isalso referred to herein as a load or challenge solution. That influentintroduction can be carried out by pumping, gravity flow, or simplediffusion as is well known.

The pre-sample solution is maintained in contact with the insolubleoxidizing medium for a time period sufficient for trivalent arsenicpresent in the influent to react with the oxidizing sites to oxidize topentavalent arsenic to form a sample solution and a reduced medium. Thesample solution is then discharged from the vessel as an effluent ofpentavalent arsenic ions.

The influent arsenic-containing aqueous solution is typically providedfrom a ground or surface water source, such as a well. In a preferredprocess, the aqueous solution has an initial trivalent arsenicconcentration of more than about 10 parts per billion.

In preferred embodiments, the trivalent arsenic oxidation is coupled toremoval of the pentavalent arsenic that is formed so that a process forremoving or reducing the concentration of trivalent and pentavalentarsenic in an arsenic-containing solution is contemplated. Thus, in oneembodiment, the effluent from the oxidation is contacted with apentavalent arsenic binding medium such as conventional strong baseanion exchange resin that binds pentavalent arsenic and that contact ismaintained for a time period sufficient for the pentavalent arsenic tobind to the ion exchange resin and formed pentavalent arsenic boundresin and an aqueous composition. Other pentavalent arsenic bindingmedia include manganese silicate, alumina, alumina/iron oxide physicalmixtures and iron oxide deposited on alumina.

The oxidizing medium can be mixed together with another pentavalentbinding medium, thereby forming a mixed-bed medium capable of oxidizingtrivalent arsenic and binding pentavalent arsenic. The maintenance timesfor oxidation and binding to the binding medium can be the substantiallysame when the two materials are physically mixed in the same vessel inthat sorption of pentavalent arsenic from the sample solution occurssubstantially as the oxidized ions are formed, so that those times arenot differentiated during usage. The maintenance times for both stepsare typically very similar even when the oxidation medium and bindingmedium are in physically separated vessels.

The aqueous composition is then discharged from the ion exchangeresin-containing vessel as an effluent having final arsenicconcentration of about zero to about 2 parts per billion;

The pentavalent arsenic binds poorly to the quaternized N-pyridiniumvinylbenzyl groups present in the oxidizing medium. This finding isquite the contrary to the findings reported in U.S. Pat. No. 5,908,557in which the N-alkyl pyridinium groups bound well to formed pentavalentarsenic ions, and those N-alkyl pyridinium groups could be used toremove the formed pentavalent arsenic from the aqueous solution. Thisdifference in binding was unexpected, but was found useful in thatpentavalent arsenic (arsenate) ions do not apparently displace triiodideor tribromide counter ions to the N-pyridinium vinylbenzyl groups,thereby maintaining the oxidative capacity of the medium.

Preferably, the pentavalent arsenic binding medium and oxidizing mediumare provided so that contact with the influent occurs in a serial mannersuch that fresh pentavalent arsenic binding medium is provided to theaqueous composition “downstream” of the oxidation medium in the same ora second vessel. The oxidizing medium and adsorption medium can beprovided in the same vessel in unmixed, separate layers, for examplesuch that the influent solution first encounters the oxidizing medium,followed by the adsorption medium. Alternatively, after contacting theoxidizing medium, the aqueous composition containing pentavalent arseniccan be introduced into a second vessel containing adsorption medium.

The arsenic-containing aqueous solution is typically provided from aground or surface water source, such as a well. In a preferred process,the aqueous solution has an initial trivalent and pentavalent arsenicconcentration of more than about 50 parts per billion.

A contemplated triiodide-reacted or tribromide-reacted insolubleoxidizing medium is dark brown or red-orange in color, respectively.Upon contact of the colored insoluble oxidant with trivalentarsenic-containing aqueous streams, the characteristic dark brown orred-orange color is discharged, yielding a light tan medium that is thecolor of starting polymerized N-pyridinium vinylbenzyl medium. Thus,conversion of trivalent arsenic to pentavalent arsenic by a contemplatedinsoluble oxidizing medium of this invention is a self-indicatingprocess.

In preferred practice, it is contemplated that contact between thearsenic-containing aqueous solution and the oxidizing medium be carriedout in a chromatographic column or flow-through container, such as aperforated plastic or mesh pouch containing adsorption particles, e.g.,a “tea bag”. A glass or plastic (e.g. polyethylene or polypropylene)column is a particularly preferred vessel for use herein and has aninlet for receiving an aqueous sample solution prior to contact of thesample solution with a medium and an outlet for the egress of waterafter contact with the medium. In such use, the media are preferably inthe form of solid beads or particles. It is noted, however, that anotherphysical form such as a liquid, powder, membrane, sheet or other web canalso be utilized.

Contact between the pentavalent arsenic binding medium and the aqueouspentavalent arsenic-containing sample solution is maintained for a timeperiod sufficient for the pentavalent arsenic to be bound by the medium.That binding is usually quite rapid, with contact times of a few secondsto a few minutes typically being utilized. Much longer contact timessuch as a few hours can be utilized with no ill effect being observed.

Contact between the oxidizing medium and the aqueous trivalentarsenic-containing solution is maintained for a time period sufficientfor the triiodide to oxidize the trivalent arsenic to pentavalentarsenic. The reaction is rapid. Use of an oxidizing medium comprised ofpolymerized N-pyridinium vinylbenzyl triiodide or tribromide moietiespermits the arsenic oxidation to be conveniently monitored byobservation of the color change from the dark brown color of thetriiodide or red-orange tribromide complex to the light tan color of thereduced N-pyridinium vinylbenzyl oxidizing medium.

The contact time is conveniently controlled by changing the flow ratethrough the column or flow-permissive container. The time that thesolution is maintained in contact with the adsorption or oxidizingmedium is the “solution residence time”.

The flow, temperature and pressure constraints of the process aredictated primarily by the limitations of the equipment utilized and theresin used in carrying out the invention. Ambient temperature andpressure are normally used.

A contemplated trivalent arsenic oxidizing process successfully oxidizestrivalent arsenic in arsenic-contaminated aqueous solutions attemperatures between about 15° C. and 90° C. Preferably, the process isoperated at temperatures between about 20° C. and 70° C.

The present trivalent arsenic oxidation process successfully providesaqueous pentavalent arsenic at a pH value from acidic to about neutral(about pH 1 to about pH 7). Preferably, the process is operated with asolution having a pH value between about 4 and 7, and most preferably,between about 6 and 7. At pH values above about 7, the process begins tolose efficiency.

A more general process for oxidizing a water-soluble metal ion from afirst oxidation state to a second, higher oxidation state is alsocontemplated. This process comprises the following steps.

a) A vessel, as discussed before, is provided that contains a solidwater-insoluble polymeric oxidizing medium having a plurality ofoxidizing sites that are N-pyridinium vinylbenzyl triiodide ortribromide moieties as discussed previously.

b) A volume of an influent aqueous solution that contains metal ions ofa first oxidation state as water-soluble ions is introduced into thevessel to contact the insoluble oxidizing medium to form a solid/liquidadmixture.

c) The solid/liquid admixture is maintained for a time period sufficientfor the metal ions present in the influent to react with the oxidizingsites to oxidize to a second, higher oxidation state to form a samplesolution and a reduced medium.

d) The sample solution is then separated from the reduced medium.

Exemplary metal ions that can be so oxidized include iron, manganese,arsenic, antimony, mercury and chromium. In some instances, the oxidizedmetal ions remain in solution, whereas in others, the oxidized metalions bind to the oxidizing medium and form medium-bound metal ions. Inthe former instance, as with iron and arsenic ions, the solid and liquidphases need only be physically separated to separate the sample solutionfrom the reduced medium. In other instances, the sample solution isseparated from the reduced medium by contacting the reduced medium witha stripping solution comprised of an aqueous salt solution.

Another aspect of the invention contemplates modified particulatealumina containing meta-periodate ions substantially homogeneouslysorbed throughout the particles. The particles are often referred toherein as A/P particles. The meta-periodate ions are present in anamount of about 0.1 to about 0.15 molar in a gravity-settled volume ofparticles in deionized water. Sodium or potassium cations are thepreferred counterions for the periodate ions. A lesser amount ofmeta-periodate anions can be present, but use of such an amount can bewasteful.

These A/P particles are useful as intermediates in forming the iron- ormanganese-containing particles discussed below. These particles are alsouseful in removing manganese, iron, cobalt and mercury ions from aqueouscompositions, which ions can be in a lower -ous or higher -ic oxidationstate, such as ferrous or ferric, manganous or manganic, mercurous ormercuric of cobaltous or cobaltic ions. These A/P particles are alsouseful for removing harmful bacteria such as coliforms from water. Indried form, A/P particles can be used in an air filter.

A further aspect of the invention contemplates modified aluminaparticles containing iron (A/I particles) or manganese (A/M particles)or both substantially homogeneously sorbed throughout the particles. Theiron or manganese is present in an amount of about 0.05 to about 0.15molar in a gravity-settled volume of particles in deionized water. Wheniron is present in the absence of manganese, the iron concentration ispreferably 0.1 to about 0.15 molar. When manganese is present in theabsence of iron, the manganese is present in an amount of about 0.50 toabout 0.075 molar. When both are present, the amount of iron and theamount of manganese typically is determined from the feed proportion,with the understanding that manganese requires two electrons per atomwhereas iron requires only one for oxidation. The particles contain anoxidized iodine species and are substantially free of molecular iodine.

A process for removing arsenic or antimony +3 or +5 ions from a watersupply is also contemplated. That process comprises the following steps.

a) An aqueous solution that contains arsenic or antimony +3 or +5 ionsin a concentration greater than about 2 parts per billion is contactedwith modified alumina particles. That solution can contain one throughall four of those ions (Sb⁺³, Sb⁺⁵, As⁺³ and As⁺⁵). Those modifiedalumina particles contain iron or manganese or both sorbed substantiallyhomogeneously distributed throughout in an amount of about 0.05 to about0.15 molar as measured in a gravity-settled volume of particles indeionized water. The particles also contain an oxidized iodine speciesand are substantially free of molecular iodine.

b) That contact is maintained for a time period sufficient for arsenicor antimony +3 or +5 ions present to be sorbed by the particles to formarsenic- or antimony-containing particles and an aqueous solution havinga lessened amount of arsenic or antimony. The contact can be at a flowrate of about one bed volume (b/v) per minute, or slower.

c) The arsenic- or antimony-containing particles are separated from theaqueous solution having a lessened amount of arsenic or antimony. Thatseparation can be by the simple procedure of passage of the aqueoussolution through a column of the alumina particles. The particles andaqueous solution can also be separated by centrifugation, filtration andthe like that are well-known to skilled workers.

In some preferred embodiments, water from which the ions are to beremoved is first passed through a bed of a before-describedwater-insoluble polymeric oxidizing medium to convert the +3 ions into+5 ions that can be more readily sorbed by the alumina particles. Thewater-insoluble polymeric oxidizing medium is preferably retained withina column as are the alumina particles.

EXAMPLES Example 1 Preparation of a Polymeric Medium

One process for preparing the 2 percent DVB cross-linked resin includesmixing gelatin (about 1.35 grams), poly(diallyldimethylammoniumchloride) (about 12.3 grams), boric acid (about 5.1 grams), and water(about 450 grams) in a flask. The mixture is adjusted to a pH ofapproximately 10.0 with 25 percent aqueous sodium hydroxide.

A solution of styrene (about 214 grams), chloromethylstyrene (about 75grams), technical grade 55 percent divinylbenzene (about 10.9 grams),and azobisisobutyronitrile (about 1.5 grams) is then added to the flask.The material in the flask is heated to a temperature of about 70° C.,continuously stirred, and maintained under a nitrogen purge forapproximately 17 hours during which time cross-linking occurs.Cross-linking causes generally spherical shaped droplets to form.Polymerized spheres are then removed from the mixture. Thechloromethylated co-polymer is soaked at room temperature in a solutionof 10 volume percent pyridine in water until titration indicates thatgreater than 90% of the chloromethyl groups are consumed.

In another process, a benzyl pyridinium chloride co-polymer was obtainedfrom the Purolite Company of Bala Cynwyd, PA under the designationA-560. This material is water-insoluble, generally spherical in shapeand macroreticular. This material has a stated capacity of 1 meq/mL ofchloride and a moisture content of about 59.7 percent. The particle sizedistribution shown is in the Table below. Particle Size DistributionDiameter (microns) Percentage <300 Zero <425 0.8 <500 6.5 <630 95.6 <71097.5Median Diameter = 568 microns

One liter of the above benzyl pyridinium resin was slurried with 1.0-2.0liters of deionized water in a glass 4 L beaker equipped with anoverhead stirrer. With rapid stirring, 500 mL of a 0.5 N KI₃ solutionwas added in a steady stream (over about 10-15 seconds) at roomtemperature to the water/resin slurry. Within about 1-5 minutes, thedark brown KI₃ solution became colorless and the light tan resinparticles became the brown polymeric medium contemplated herein. Thepolymeric medium particles are typically filtered and rinsed withdeionized water to remove the potassium chloride that is formed. Theresulting polymeric medium contains about 0.25 moles of I₃ ⁻ per liter.

In another preparation, a batch of the A-560 resin was stirred by anoverhead paddle stirrer in a 2 liters of 1.0 M NaBr in water for a timeperiod of 30 minutes at ambient room temperature to form a suspension.Liquid bromine (80 g; 0.5 moles) was added to the stirring suspension ina steady stream over a 2-3 minute time period, with the stirringcontinuing for about an additional 5 minutes after the addition wascomplete. The Br₃ ⁻ ion-containing resin was a bright orange-red colorand the supernatant was colorless. The resin was filtered, washed with8-10 liters of fresh deionized water and air-dried at room temperatureuntil free flowing. No odor of bromine was noted from the resultingdried tribromide resin.

Example 2 Iodine Elution

Two studies were carried out to assess the ease with which iodine couldbe eluted from a contemplated polymeric medium. In the first study, astrong base anion exchange resin in triiodide form denominated A-605available from Purolite Company, Bala Cynwyd, Pa. was compared to acontemplated polymeric medium. The A-605 resin was said to be a styrenedivinylbenzene gel resin having a wet screen size of about 16 to about50. The contemplated polymeric medium was a chloromethylated styrenedivinylbenzene that was reacted with pyridine, and the chloride presentwas exchanged for triiodide to provide about 0.2 moles of triiodide perkilo.

In the first study, using the procedure of PSTM-95 (Product StandardTest Method-95) that involved eluting a sample of the assayed materialwith sodium hydroxide and back titration of an aliquot with sodiumthiosulfate showed that the A-605 contained 12 grams of iodine per 25 mLof resin, whereas no iodine was found by this procedure using thecontemplated polymeric medium.

In a second study, a sample of the A-605 resin or another sample of thebefore-described polymeric oxidative medium in triiodide form was elutedwith dechlorinated Philadelphia city water at a rate of 10 bed volumes(bv) per minute. Portions of the eluent were collected at 50, 100 and150 bed volumes and analyzed for free iodine using the leuco crystalviolet method of the AWWA “Standard Methods for the Examination of Waterand Waste Water” 20^(th) edition (American Water Works Association, 6666West Quincy Ave., Denver Colo. 80235). Iodide ion was also assayed for,but those data obtained are suspect and are not reported here. Theresults are shown in the Table below. Iodine Water Elution Study SAMPLEFREE I₂ (mg/L) A-605 50 bv 2.2 100 bv 2.2 150 bv 2.2 Polymeric Medium 50bv 0.03 100 bv 0.04 150 bv 0.04

As is seen from the data, the A-605resin lost iodine at a considerableand substantially constant rate over the course of the study, whereas acontemplated polymeric oxidative medium lost substantially nothing overthat same course of study.

In a positive control study, a small portion of each material assayedabove was contacted with 0.1 N sodium thiosulfate for about 18 hours(over night). On mixing, each material immediately turned from a darkpurple color to tan. An aliquot of each supernatant liquor was removedand titrated with 0.01 N iodine to the starch end point. The resultsshowed that the A-605 resin contained 12 grams of iodine/25 mL resin,whereas the contemplated polymeric medium contained 1.4 grams of iodineper 25 mL of resin.

Example 3 Preparation of Aseptic Water

A 40 gallon water tank used for recirculating water for a decorativepool was connected in a closed system to a column containing 300 mL of acontemplated polymeric medium supported on a porous frit. A pumpmaintained a flow rate of 450 mL per minute through the column ofpolymeric medium.

One hundred milliliter aliquot samples were taken from the tank on Aug.23, 2000 and again on Oct. 25, 2000. Each of the samples was assayed byG&L Laboratories of Quincy, Mass. for Pseudomonas aeruginosa andLegionella present in each of the aliquots using colony-forming standardassay procedures. The results of that study are shown in the MicrobialAssay Table below. Microbial Assay Colonies Colonies on Microbe on Aug.23, 2000 Oct. 25, 2000 Pseudomonas aeruginosa 140 3 Legionella <2 <1

As can be readily seen, a contemplated polymeric medium was particularlyuseful in reducing the load of Pseudomonas aeruginosa in the water tank.

Example 4 Coliform Removal

Several liters of water from the Rock River were obtained fromdownstream of the sewerage treatment plant in Rockford, Ill.Approximately one liter of that water was decanted and contacted withand eluted through about 20 mL of a triiodide form of the polymericmedium as described in Example 1 supported on a porous frit in a columnat a flow rate of about one-half bed volume (about 10 mL) per minute.About one hundred mL from the pooled eluate were assayed for coliformand E. coli using commercial coliform and E. coli presence/absence assaykits (Hach Co., Loveland , Colo. Catalogue No. 23232 and No. 24016)following the kit instructions. The assays of the eluate were negativefor the presence of coliform and E. coli after an extended incubationperiod, whereas a similar assay carried out on the original sample ofRock River water as a control was positive for coliform and E. coliafter only a few hours of incubation. The polymeric medium-treated wateralso changed color from yellow to colorless.

Example 5 Arsenic Oxidation and Removal

Oxidation of arsenic from the trivalent to the pentavalent form isrequired when using a variety of conventional technologies for arsenicremoval such as reverse osmosis and conventional anion exchange resins,neither of which recognize trivalent arsenic. The following studies werecarried out to illustrate the oxidation properties of a N-pyridiniumvinylbenzyl triiodide group-containing oxidation medium disclosedherein.

A challenge solution comprised of one liter of tap water spiked toprovide a trivalent arsenic concentration of 500 ppb. The pH value ofthe arsenic-containing tap water composition was adjusted to 6.8-7.0.

To a 50 mL burette with a stopcock and polyglass frit were added 5 mL ofa before-described N-pyridinium vinylbenzyl triiodide group-containingoxidation medium that provided about 0.1 M triiodide to form Column A. Asimilar column, Column B, was prepared using 5 mL of a Type II strongbase anion exchange resin. The latter resin is understood to be aco-polymer of styrene and divinylbenzene that is chloromethylated andthen reacted with (2-hydroxyethyl)-dimethylamine, and is available fromSybron Chemicals Inc. under the designation ASB-2. Columns A and B werepacked using tap water. The effluent from the column packing wasconcentrated 20-fold and tested for the presence of arsenic using acommercially available calorimetric Gutzeit Arsine Generation test [EMScience (Merck)] that is able to detect 100 ppb to 3000 ppb arsenic. Theresults were negative.

Procedure 1

Ten bed volumes (bv; 50 mL) of the challenge solution containing 500 ppbof trivalent arsenic were passed through the bed of Column B at a flowrate of 1 bv per minute and collected. The effluent tested at 500 ppb.

Procedure 2

Ten bv of the challenge solution containing 500 ppb of trivalent arsenicwere passed through the bed of Column A at a flow rate of 1 bv perminute and collected. The collected effluent was then passed through thebed of Column B at the same flow rate and collected. The effluent fromColumn B was concentrated and assayed for total arsenic with a result ofthere being less than 5 ppb present.

Procedure 3

Procedure 2 was repeated except that the flow rate through Column A wasincreased to 2 bv per minute. The assay for arsenic after passagethrough Column B and concentration was again less than 5 ppb.

Procedure 4

Procedure 2 was again repeated except that the flow rate through ColumnA was increased to 3 bv per minute. The result was again the same.

The above results illustrate that a contemplated N-pyridiniumvinylbenzyl triiodide group-containing oxidation medium could oxidizethe challenged amount of trivalent arsenic and convert it to thepentavalent form that could be removed from the flow stream by aconventional anion exchange resin.

A similar, more qualitative, result was also obtained using well waterfrom the area around Lake Winnebego in Wisconsin, near the city ofOshkosh. Here, the well water contained about 60 to about 120 ppb totalarsenic and about 5-10 ppm iron. The arsenic was separately shown to beabout 60-70 percent trivalent.

Approximately 74,000 gallons of well water for a home were passedthrough a commercially available iron removal system and thereafterthrough about ⅔ cubic foot of a before-described N-pyridiniumvinylbenzyl triiodide group-containing oxidation medium containing about0.2 M triiodide. The effluent water from the oxidation medium thenpassed through an iron oxide on alumina sorbent column to removepentavalent arsenic and then into the home.

The iron oxide on alumina sorbent was prepared as discussed below. Alaboratory of the State of Wisconsin found no detectable arsenic onassay of the effluent water after removal of pentavalent arsenic, with alimit of detection of 0.8 ppb. Those assay results also indicated nodetectable iron with a detection limit of 0.01 to 0.02 ppm. Theseresults also show that the kinetics of oxidation are relatively rapid.

The iron oxide on alumina sorbent was prepared as follows. Ten liters of0.125 M sodium metaperiodate (NaIO₄) were prepared in deionized water towhich a few drops of sulfuric acid were added. The solution was placedinto a 5 gallon plastic carboy. Alumina (Al₂O₃), 28-48 mesh, (AlcanAA400G) was scooped into the carboy until the solid reached the original10 L volume, so that the container held about 12-14 L. The carboy wasclosed and rolled on a drum roller for a period of about 2 to 3 hours.Samples were taken from time to time from the supernatant and testedwith starch iodide paper to test for free metaperiodate.

Once the supernatant was free of metaperiodate, the mixture was filteredunder reduced pressure through a Buchner funnel using plastic windowscreen as the filter. The filter cake was rinsed with deionized waterand then dewatered with the aspirator.

The filtered metaperiodate-treated alumina was added back to the carboyand 10 L of 0.125 M ferrous ammonium sulfate {Fe[(NH₄)SO₄]₂} wereadmixed with the metaperiodate-treated alumina. The carboy was closedand the contents mixed by rolling for about 12-16 hours (over night).The surface of the alumina became dark brown in color from the whiteoriginal color, and after the mixing period, the supernatant liquidtested negative for iron using a commercial test paper with asensitivity of about 100 ppm. The iron oxide on alumina sorbent soprepared was filtered and used as described above.

Example 6 Comparative Dichromate Binding

A qualitative study was conducted of relative rates at which dichromateion is bound by an adsorption medium contemplated herein and anadsorption medium disclosed in Smith et al. U.S. Pat. No. 5,908,557. Anadsorption medium contemplated here contains pendent benzyl pyridiniumgroups, whereas an adsorption medium of Smith et al. contains pendentN-alkyl pyridinium groups.

In a first study, a 20 mL capacity chromatography column equipped with aporous frit was charged with 15 mL of PERFIX™ resin (chloride form) ofSmith et al. slurried in water. This adsorption medium contains about 2equivalents per liter (eq/L) of quaternary groups. The column waspermitted to flow at a rate of 10 mL per minute and was challenged withabout 10 mL of an aqueous solution containing 1000 ppm of sodiumdichromate (1 g/L) at a pH value of 7. A sharp yellow-orange band ofbound formed immediately at to top of the column, indicating rapidtake-up of the challenge.

A similar study was carried out with an adsorption medium contemplatedherein using the same amount of medium, also in chloride form, at thesame flow rate. Repeating the above challenge with the sodium dichromatesolution at the same flow rate provided a vertically diffuseyellow-orange band with some breakthrough of dichromate. Incubation forseveral hours resulted in complete take up of the dichromate ions.

These results indicate that there is a major difference in binding ratebetween the two adsorption media towards dichromate ion. Thus, eventhough there were more than enough binding sites available in eachmedium, one medium bound the dichromate ions almost instantly, whereasthe other took several hours to bind the dichromate ions. On the otherhand, both materials appeared to adsorb triiodide ions at about the samerate.

Example 7 Preparation of a Further Alumina/Meta-Periodate Complex

To a 12 gallon plastic graduated carboy (Nalgene Corp.) was added 30liters of deionized water to which 1-2 mL of concentrated sulfuric acidwas added. To the dilute acid solution, 800 cm³ of solid, sodiummetaperiodate was added. The periodate was dissolved by means of anoverhead paddle stirrer. Solution was achieved in about 30 minutes atroom temperature. The addition of sulfuric acid hastens the solution ofmeta-periodate salt but is not essential.

After solution was achieved, the stirrer was removed and solid, dry,activated alumina 28/48 mesh was scooped into the carboy with the aid ofa wide-mouth funnel until the alumina level in the carboy was equal tothe 30 liter mark (approximately 23 kg dry weight). The carboy cap wasreplaced and the carboy and contents, about 38 liters total reactionvolume, was placed on its side and rolled periodically by means of amechanical drum roller or by manually rolling the carboy across a flatsurface such as a floor. Rolling was best accomplished in 2-3 minuteintervals to insure good mixing but avoiding conditions that promotedparticle size reduction through milling.

After 4-5 rolling cycles, the carboy was placed upright and allowed toremain undisturbed overnight. At the end of this period, finesassociated with the raw material alumina had settled leaving a clean,light yellow supernatant that tested negative for meta-periodate ionusing starch/KI indicator solution. This indicated that all of themeta-periodate had bound to the alumina particles.

The meta-periodate-loaded alumina particles were removed from the carboyby pouring and sluicing by means of a water stream. Alumina/periodateparticles were collected on a horizontal plate filter equipped with awindow screen mat that permitted fines to pass through. The collectedparticles were washed with tap water until the effluent stream from thefilter pot was relatively free of fines. Washes containing fines werecollected in appropriately sized vessels or jugs allowing fines tosettle prior to discarding the wash water mixed with reactionsupernatant.

Alumina/periodate particles remaining on the filter screen are furtherde-watered by applying a water aspirator vacuum to the filter.Alumina/periodate (A/P) can be used directly at this point forpreparation of alumina/iron complex or alumina/manganese complex. (SeeExamples 2 & 3) Alternatively, the de-watered alumina/periodateparticles can be further dried (until free flowing) by loading in traysand air open- or oven-dried. The oxidation ability of dried A/P wasretained over at least several months as ascertained by challenging withaqueous manganous (Mn II) or ferrous (Fe II) ions that result incharacteristic colors formed within and upon the white A/P.

The scale of A/P production is easily modified by following the protocolof this example. For instance, batches of A/P 10-times larger thandescribed here have been processed substituting a rotary cone vessel forthe carboy and a centrifuge equipped with window screens for thehorizontal plate filter. Additionally, activated alumina of differentmesh size or shape; i.e., spherical, can be processed as in this examplewith essentially the same results.

Example 8 Preparation of Alumina/Iron (A/I) Complex

Thirty liters of alumina/periodate (A/P) prepared in Example 7 wereplaced in an empty, 12 gallon plastic carboy along with sufficient roomtemperature de-ionized water to just cover the A/P particles. Next, asolution of ferrous ammonium sulfate was added to the carboy prepared bydissolving 3.7 moles of the above salt (1.47 kg of monohydrate, mw 392)in about 2.5-3 gallons (about 10 liters) of room temperature de-ionizedwater.

The capped carboy's contents were mixed immediately by placing thecarboy on its side and rolling on a flat surface or a mechanical drumroller. Mixing by rolling is continued at 1-2 minute intervals for 1-2hours. After this time period, a test for ferrous ion remaining in thereaction supernatant is negative. Test strips for iron (II) from EMScience (Gibbstown, N.J. 08027) sensitive to 10 ppm are convenient formonitoring iron uptake by the A/P. The uptake of iron ion by the A/Pparticles was rapid and can be noted visually by the immediate change incolor of the white A/P particles to a dark, rust-brown color ofalumina/iron (A/I) particles upon adding and mixing the solution offerrous ions to the A/P in the carboy.

The resulting A/I particles were filtered, washed and dried per theprocedure described in Example 7. As described in Example 7, theprotocol described here for production of A/I is effective for smalleror larger batch sizes or for different mesh sizes and shapes of A/P.Dried or wet A/I is stable indefinitely and does not bleed iron oraluminum when challenged with an aqueous flow in a pH value of about 5.5to about 8.5.

A/I particles prepared by this example and elsewhere herein are readilydistinguishable from iron-alumina composites described by PCT WO99/50182. The PCT application describes and claims a “coating” ofinsoluble ferric oxide formed by precipitation of iron (III) hydroxideonto the alumina carriers. This coating process results in aheterogeneous particle having a “salt and pepper” appearance and anunknown impact on the native, porous structure of the alumina carrier.A/I particles prepared by this example have a homogeneous appearancefrom particle to particle and throughout the entire volume and mass ofeach individual particle. A/I particles prepared herein are believed tohave iron grafted onto and into the alumina matrix through an unknownstructure mediated by the meta-periodate-alumina complex prepared inExample 7.

It was surprising that meta-periodate bound to alumina serves both as anoxidant and complexing agent to the challenging ferrous ions. A/Iprepared by this method when re-challenged with fresh ferrous ammoniumsulfate solution slowly liberates free, elemental iodine (I₂) asevidenced by iodine crystals forming and purple color in the vaporphase. A positive starch test was also observed.

A/I particles prepared by this example thus have residual meta-periodateion (or similar oxidant) in some form as an integral component. A/Iparticles are a substantially homogeneous composition of iron in anunknown bonding state, an oxide of iodine and alumina. WO 99/50182describes a composite of iron oxide carried as a coating on alumina.

Example 9 Preparation of Alumina/Manganese Complex

Manganous sulfate tetrahydrate (MnSO₄.4H₂O; MWt 223; 836 g) wasdissolved in approximately 10 liters of deionized water at roomtemperature, was added to 30 liters of A/P (Example 7) in a 12 gallonplastic carboy and mixed by periodic rolling in a manner described inExamples 7 or 8. The resulting uniformly black particles ofalumina/manganese (A/M) were filtered, washed and dried in an analogousmanner to that described for the preparation of A/I given in Example 8.A/M particles are a dark-brown (black when wet) complex of alumina, anoxide of iodine and an oxide of manganese, probably Mn⁺⁴. A/M was foundto be stable indefinitely.

Example 10 Use of A/P to Mitigate Naturally Iron and Manganese inPotable Water

In Examples 9 and 8 above, ferrous or manganous ions were intentionallyadded to A/P particles to produce the derivatives A/I and A/M, whichhave utility for mitigation of arsenic and antimony from water. Groundwater intended for potable use is frequently contaminated withindigenous Fe⁺² and/or Mn⁺². Although not posing a health hazard,indigenous iron and manganese can cause staining of clothing or manifestthemselves as unsightly precipitates in packaged bottle water. Iron andmanganese impurities are known to foul reverse osmosis membranes.

A 2 liter capacity plastic cartridge with top and bottom porous fritswas loaded with approximately 2 liters of A/P matrix, plumbed andmounted vertically on the hot-water intake line of a household clotheswashing machine. Feed water to the A/P cartridge averaged 10 ppm Fe and0.5 ppm Mn. Water leaving the A/P cartridge and feeding the washer hadnon-detectable iron and manganese, was colorless, and did not stainclothing.

In an average household, a 2 liter A/P cartridge can provide iron-free,manganese-free water for a period of several months. In this example,A/I and/or A/M are formed in-situ with indigenous Fe and/or Mn.Indigenous arsenic co-mingled with naturally occurring iron or manganesebinds to the in-situ generated matrix.

Example 11 A/P Particles for Coliform Removal

The studies of Example 4 were repeated using A/P instead of the organicpolymer to remove the bacteria. The conditions used and the resultsobtained were substantially identical when using A/P particles. A/P isnonflammable and can be useful in aircraft cabin air filters in dryform.

Example 12 A/P Particles to Mitigate Mercury from an Aqueous Composition

A glass chromatographic column with bottom porous glass frit and bottomTeflon® stop-cock was loaded with 25 mL (settled volume) of A/Pparticles added to a standing volume of 50 mL of deionized water. Anyair trapped in the A/P bed was expelled by gentle rocking of the column.Flow was initiated by opening the stop-cock partially and manuallyadjusting flow at about 10 mL/minute, while periodically adding freshdeionized water to the top opening of the column to maintain a 2-10 cmhead over the A/P.

Next, 500 mL of a standard solution containing 100 ppm of mercuric salt(nitrate) was periodically added to the top opening of the column, whilemaintaining a flow rate of approximately 10 mL/minute. Fifty mLfractions eluting from the column were tested for mercury(diphenylcarbazone test (see Feigl, Qualitative Analysis By Spot Test,Elsevier Publishers, 1946 p. 48) at a sensitivity of detection of 5 ppm.All fractions tested at less than 5 ppm, indicating removal efficiencyof removal of more than 95 percent.

During the course of mercury standard addition, a distinct orangecolored band formed at the top of the A/P bed (white), which lengthenedduring the course of the challenge. Measurement of the colored bandheight compared to the total height of the 25 mL extrapolates to anapproximate capacity of one pound of mercury per cubic foot of A/Pmedium. Because A/P is non-flammable, mercury captured by A/P isrecoverable by conventional roasting/retorting techniques.

Example 13 Use of A/P Particles for the Mitigation Cobalt in AqueousStreams

An apparatus and procedure similar to that described in Example 12 wasemployed to investigate mitigation of cobalt (II) from an aqueousstream, e.g., a chromatographic column was loaded with 25 cc of A/Pparticles and challenged with a 500 ppm (Co⁺²; cobaltous) cobalt (II)standard solution. Fractions of 50 mL were collected and scrutinized forcobalt content using test strips sensitive to 10 ppm (EM Science,Gibbstown, N.J.). The pH value was maintained at 6-7 and flow rate wasmaintained at approximately 0.5 bv/minute.

During the course of the cobalt (II) challenge, an olive green bandformed on the top of the A/P column, which lengthened as the testproceeded. All fractions tested negative for cobalt indicating more 98percent mitigation of cobalt (II) added. Cobalt is problematic for thenuclear power industry where radioactive cobalt⁶⁰ contaminates certainprocess waste water. A/P particles with sorbed Co⁶⁰ can be integratedinto ceramics or concrete for ultimate disposal.

Example 14 A/I Particles for Removing Arsenic (V) or Antimony (V) fromAqueous Streams

Using a laboratory glass column (described in Example 13 and 14) 25 ccof A/I particles (Example 8) was loaded and equilibrated with deionizedwater. A challenge of tap water spiked with 500 parts per billion (ppb)of arsenic (V) was passed through the A/I bed while periodicallyexamining effluent for arsenic (Hach test kit, Loveland, Colo.;sensitivity: 10 ppb).

In this example, arsenic-spiked test water was delivered from areservoir and onto the column by means of a peristaltic pump set todeliver 15 mL/minute. In total, 1200 bed volumes (30 liters) of testsample were passed through the column. Arsenic determinations were madeon each 1 liter increment of effluent and revealed less than 10 ppbarsenic on all fractions by the Hach test. Effluent samples furtherconcentrated to 1/10 their original volume (U.S. Pat. No. 5,908,557)revealed effluent arsenic concentration of less than 1 ppb.

When this example was repeated using 500 ppb antimony (V) spiked tapwater, effluent water revealed less than 5 ppb antimony as determined byatomic absorption.

Example 15 Comparison of A/I Particles to Particles Prepared as in WO99/50182

An iron oxide-alumina composite described in WO 99/50182 is commerciallyavailable (Alcan Aluminum Co., Brockville, Ontario, Canada) as AAFS50.That material is further described by its manufacturer as aluminacontaining 6.0 percent Fe₂O₃ (about 4.2 percent Fe) by weight. Althoughplain activated alumina has an inherent ability to bind arsenic V,clearly, as demonstrated in WO 99/50182, AAFS50 is a vastly superioradsorbent for arsenic as compared to plain activated alumina.

A/I particles of this invention contain a calculated maximum of 0.7percent by weight of Fe. Visually, A/I appears to have a darker, moreintense and uniform rust color compared to AAFS50 particles that arespeckled, non-uniform, an much lighter in color. AAFS50 particlessubjected to crushing (mortar and pestle) reveal a white core within theparticle indicating a coating of Fe₂O₃ on the exterior. Similar crushingof A/I particles reveal a uniform, dark rust color throughout theparticles.

Accelerated performance comparisons with A/I and AAFS50 particles weremade on the chromatographic format previously described utilizing a 1000ppb (1 ppm) As⁺⁵ challenge applied at 0.25 bv/minute. At this level ofchallenge, AAFS50 particles revealed a “breakthrough” of 10 ppb at about500 column volumes, whereas A/I particles did not show a 10 ppb As⁺⁵breakthrough until after 600 bv. This example demonstrates that thetotal quantity of Fe present (AAFS20=4.2 percent) A/I=0.7 percent) isnot as important as how the iron is presented to the challenge stream.

It is not known how the coating process for AAFS50 particles affects theeffective porosity of the sorbent particles. The significant improvement(more than 20 percent) of A/I particles in capturing arsenic V in spiteof having ⅙ the amount of total Fe may be due in part to the nature ofthe iron/iodine oxide/alumina complex and in part to a more functionallyeffective pore structure.

The capacity of a particular sorbent for a target ion is only onemeasure of efficiency. Another important parameter of efficiency is therate at which a sorbent takes up and mitigates a target ion down toacceptable levels. When the experiment related in this example wasrepeated at increased flow rate (1.0 bv/minute vs. 0.25 bv/minute)arsenic at levels more than 10 ppb were noticed instantly in theeffluent of the AAFS50 column, whereas no arsenic was detected in theeffluent of the A/I column at 1.0-2.0 bv/minute. Thus, A/I particlessorb As⁺⁵ at a rate that is at least 4 times faster than sorption byAAFS50 particles. In practical terms, a column containing A/I particlesto mitigate As⁺⁵ need only be ¼ the size of a column of AAFS50 particlesto process the same amount of water in the same amount of time.

Example 16 A/M Particles to Mitigate As⁺⁵ or As⁺³

Twenty-five mL of A/M particles (Example 8) were challenged with tapwater containing 500 ppb of added As⁺⁵ or unchlorinated well watercontaining 500 ppb of added As⁺³ using the same chromatographic protocoldescribed in Example 13. A/M particles bound all (more than 99 percent)arsenic (either As⁺⁵ or As⁺⁵) applied. Effluent tested for manganeserevealed non-detectable amounts. It is thought that manganese present inA/M particles is tetravalent causing oxidation of As⁺³ to As⁺⁵. Any MnII produced from such a reaction remains insoluble.

Each of the patents and articles cited herein is incorporated byreference. The use of the article “a” or “an” is intended to include oneor more.

The foregoing description and the examples are intended as illustrativeand are not to be taken as limiting. Still other variations within thespirit and scope of this invention are possible and will readily presentthemselves to those skilled in the art.

1. A water-insoluble polymeric medium having a plurality of polymerizedN-pyridinium vinylbenzyl triiodide moieties whose pyridinium rings beartwo substituents, R¹ and R², that are independently a hydrido or a C₁-C₄alkyl group, said polymerized N-pyridinium vinylbenzyl triiodide ortribromide moieties corresponding in structure to the formula


2. The polymeric medium in accordance with claim 1 wherein one of saidR¹ and R² substituents is a C₁ group.
 3. The polymeric medium inaccordance with claim 1 wherein said R¹ and R² substituents are bothhydrido groups.
 4. The polymeric medium in accordance with claim 1 thathas a triiodide ion content of about 0.1 to about 1.0 moles per liter.5. The polymeric medium in accordance with claim 1 that is free ofwater-elutable iodine.
 6. A water-insoluble polymeric medium having aplurality of polymerized N-pyridinium vinylbenzyl triiodide moieties inwhich the triiodide ion content is about 0.1 to about 1.0 moles perliter, said medium being free of water-elutable iodine.
 7. The polymericmedium in accordance with claim 6 wherein the triiodide ion content isabout 0.2 to about 0.5 moles per liter.
 8. The polymeric medium inaccordance with claim 6 wherein said medium is macroreticular.
 9. Thepolymeric medium in accordance with claim 8 wherein said macroreticularmedium comprises free-flowing particles.
 10. A process for forming anaseptic fluid from a fluid containing microbial contamination comprisingthe steps of: (a) providing a vessel containing a water-insolublepolymeric medium having a plurality of polymerized N-pyridiniumvinylbenzyl triiodide or tribromide moieties of the structure

wherein R¹ and R² are independently a hydrido or a C₁-C₄ alkyl group;(b) introducing to the vessel an influent of microbially contaminatedfluid that is clear and free from visible precipitate to contact theinsoluble medium; (c) maintaining said fluid in contact with saidinsoluble medium for a time period sufficient for microbes present inthe influent to be killed by said triiodide ions and form aseptic fluid;and (d) discharging the aseptic fluid from the vessel as an effluent.11. The process in accordance with claim 10 wherein one of said R¹ andR² substituents is a C₁ alkyl group.
 12. The process in accordance withclaim 10 wherein said R¹ and R² substituents are both hydrido groups.13. The process in accordance with claim 10 wherein said polymericmedium has a triiodide ion content of about 0.1 to about 1.0 moles perliter.
 14. The process in accordance with claim 10 wherein said fluid iswater.
 15. A process for forming aseptic water from an aqueous solutioncontaining microbial contamination comprising the steps of: (a)providing a vessel containing a water-insoluble polymeric medium havinga plurality of polymerized N-pyridinium vinylbenzyl triiodide moietiesin which the triiodide concentration is about 0.1 to about 1.0 moles perliter; (b) introducing to the vessel an influent of microbiallycontaminated water that is clear and free from visible precipitate tocontact the insoluble medium; (c) maintaining said water in contact withsaid insoluble medium for a time period sufficient for microbes sent inthe influent to be killed by said triiodide ions and m aseptic water;and (d) discharging the aseptic water from the vessel as an effluent.16. The process in accordance with claim 15 wherein the influentcontains coliform or Pseudomonas aeruginosa.
 17. The process inaccordance with claim 15 wherein medium is macroreticular.
 18. Theprocess in accordance with claim 15 wherein the triiodide ion content isabout 0.2 to about 0.5 moles per liter.
 19. An apparatus for preparingan aseptic fluid that comprises: a vessel having an inlet, an outlet anda water-insoluble polymeric medium in a polymeric medium-containingregion; said water-insoluble polymeric medium comprising a plurality ofpolymerized N-pyridinium vinylbenzyl triiodide moieties whose pyridiniumrings bear two substituents, R¹ and R², that are independently a hydridoor a C₁-C₄ alkyl group, said polymerized N-pyridinium vinylbenzyltriiodide or tribromide moieties corresponding in structure to theformula

 wherein the medium is supported and contained within themedium-containing region.
 20. The apparatus in accordance with claim 19wherein one of said R¹ and R² substituents is a C₁ group.
 21. Theapparatus in accordance with claim 19 wherein said R¹ and R²substituents are both hydrido groups.
 22. The apparatus in accordancewith claim 19 that has a triiodide ion content of about 0.1 to about 1.0moles per liter.
 23. The apparatus in accordance with claim 19 that isfree of water-elutable iodine.
 24. An apparatus for preparing asepticwater that comprises: a vessel having an inlet, an outlet and awater-insoluble polymeric medium in polymeric medium-containing region;said water-insoluble polymeric medium comprising a plurality ofpolymerized N-pyridinium vinylbenzyl triiodide or tribromide moieties inwhich the triiodide ion content is about 0.1 to about 1.0 moles perliter, and is free of water-elutable iodine; wherein the medium issupported and contained within the medium-containing region.
 25. Theapparatus in accordance with claim 24 wherein the triiodide ion contentis about 0.2 to about 0.5 moles per liter.
 26. The apparatus inaccordance with claim 24 wherein said medium is macroreticular.
 27. Theapparatus according to claim 24 wherein said vessel includes a firstflow-permitting support positioned between the outlet and themedium-containing region.
 28. The apparatus according to claim 24wherein said vessel includes a second flow-permitting support positionedbetween the inlet and the medium-containing region.
 29. The separationapparatus according to claim 24 wherein said inlet and outlet areseparated from each other.
 30. The separation apparatus according toclaim 24 wherein said the inlet and outlet are at opposite ends of theapparatus.
 31. A process for oxidizing trivalent arsenic to pentavalentarsenic or trivalent antimony to pentavalent antimony comprising thesteps of: (a) providing a vessel containing a water-insoluble polymericoxidizing medium having a plurality of oxidizing sites that comprise aplurality of polymerized N-pyridinium vinylbenzyl triiodide ortribromide moieties whose pyridinium rings bear two substituents, R¹ andR², that are independently a hydrido or a C₁-C₄ alkyl group, saidpolymerized N-pyridinium vinylbenzyl triiodide or tribromide moietiescorresponding in structure to the formula

(b) introducing an influent aqueous solution having trivalent arsenic ortrivalent antimony to the vessel to contact the insoluble oxidizingmedium; (c) maintaining said solution in contact with said insolublemedium for a time period sufficient for said trivalent arsenic ortrivalent antimony in the influent to react with said oxidizing sites toform a pentavalent arsenic-containing or pentavalent antimony-containingsample solution and a reduced medium; and (d) separating the pentavalentarsenic-containing or antimony-containing sample solution from thereduced medium.
 32. The process in accordance with claim 31 wherein oneof said R¹ and R² substituents is a C₁ group.
 33. The process inaccordance with claim 31 wherein said R¹ and R² substituents are bothhydrido groups.
 34. The process in accordance with claim 31 wherein saidseparated pentavalent arsenic-containing sample solution is an effluentfrom said vessel.
 35. The process in accordance with claim 31 whereinsaid pentavalent arsenic-containing sample solution is contacted with apentavalent arsenic binding medium and that contact is maintained for atime period sufficient to form medium-bound pentavalent arsenic and anaqueous composition.
 36. The process in accordance with claim 35 whereinsaid pentavalent arsenic binding medium and said oxidizing medium are inseparate vessels.
 37. The process in accordance with claim 36 whereinsaid aqueous composition is discharged from the vessel as an effluenthaving final arsenic concentration that is at least about 95 percentless than the initial arsenic concentration.
 38. A process for removingtrivalent arsenic from an aqueous solution comprising the steps of: (a)providing a vessel containing a water-insoluble media comprising (i) anoxidizing medium having a plurality of oxidizing adsorption sites thatare containing a water-insoluble polymeric oxidizing medium having aplurality of oxidizing sites that comprise a plurality of polymerizedN-pyridinium vinylbenzyl triiodide or tribromide moieties whosepyridinium rings bear two substituents, R¹ and R², that areindependently a hydrido or a C₁-C₄ alkyl group, said polymerizedN-pyridinium vinylbenzyl triiodide or tribromide moieties correspondingin structure to the formula

 and (ii) a pentavalent arsenic binding medium; (b) introducing aninfluent aqueous solution having trivalent arsenic to the vessel tocontact the insoluble oxidizing medium; (c) maintaining said solution incontact with said insoluble oxidizing medium for a time periodsufficient for said trivalent arsenic in the influent to react with saidoxidizing sites to form an influent pentavalent arsenic-containingaqueous solution and for a time period sufficient for said formedpentavalent arsenic to bind to said binding sites to form a medium-boundarsenic and an aqueous composition; and (d) discharging the aqueouscomposition from the vessel as an effluent having a final arsenicconcentration of about zero to about 2 parts per billion.
 39. Theprocess in accordance with claim 38 wherein arsenic is present in saidinfluent at a concentration greater than 50 parts per billion.
 40. Theprocess in accordance with claim 38 wherein said oxidizing medium andsaid pentavalent arsenic binding medium are present in said vessel inlayers.
 41. The process in accordance with claim 40 wherein saidinfluent contacts said oxidizing medium layer prior to contacting saidpentavalent arsenic binding medium layer. 42.-50. (canceled)